Fluid System

ABSTRACT

The invention relates to a fluid system for a pump circuit ( 10 ), in particular a hydraulic high-pressure pump circuit, having a function block ( 12 ), in the housing of which fluid-conducting paths extend and to which valve components ( 32, 46 ) can be connected at least partially. The filter device is an at least partially integrated constituent part of the function block of the fluid system as a result of the fact that a filter device ( 46 ) with its filter housing ( 56 ) can be connected to the function block ( 12 ) in such a way that at least one filter element ( 70 ) is received in the installation space ( 72 ) of the function block.

The invention relates to a fluid system for a pump circuit, inparticular a hydraulic high pressure pump circuit, having a functionblock, in whose housing fluid-carrying paths extend and to which valvecomponents can be at least partially connected.

DE 199 34 574 C2 discloses a generic fluid system, with flow paths forgases and/or liquids, with prismatic function units and structuralunits, which as fluid-carrying paths have flow channels and in the facesurfaces have connection openings for adjacent function units andstructural units. In addition, there can be a mounting plate for theattachment of the indicated function units and structural units. Theseunits have a base surface which consists of a square with a standardedge length or which is composed of several: such squares. To build amodular building-block system consisting of the block-like functionunits and structural units as well as the valve components, the units ontheir base surface and the mounting plate have holes in a correspondinggrid for definable fastening possibilities, the structural units in therespective fastening position adjoining one another with their sidesurfaces and the connection openings in the respective valve block as aunit being enclosed by ring-shaped depressions in which there is atleast one respective gasket each which adjoins the wall of thedepression and seals it.

With the known fluid system, a type of modular system is devised withwhich a plurality of fluidic tasks can be performed, in which, totrigger the fluid-carrying paths, valve components are used, such asdirectional valves, pressure limitation valves, throttle valves, etc;but it is also possible to connect sensors and other display devicessuch as, for example, pressure gauges or the like.

If the prior art function block is, however, to interact with otherfluid components, such as, for example, hydraulic pumps, coolers, heatexchangers, filter units, etc., these additional components can beconnected to the prior art function block separately via additionalpiping; this on the one hand leads to structurally large designs and onthe other, due to the relatively long fluid transport paths, thermallyinconsistent behavior occurs; this can adversely affect the efficiencyof these fluid systems.

Proceeding from this prior art, the object of the invention is tofurther improve the known fluid system such that, in connection with theuse of filter elements as additional fluid components, less installationspace is necessary and such that improved efficiency is obtainedespecially when the most varied operating temperature ranges occur. Thisobject is achieved by a fluid system with the features of claim 1 in itsentirety.

In that, as specified in the characterizing part of claim 1, a filterdevice with its filter housing can be connected to the function blocksuch that at least one filter element is held in the installation spaceof the function block, the filter device is at least a partiallyintegrated component of the function block of the fluid system. Thisresults in a fluid system of structurally small size, in which itsindividual components are compactly combined with the valve componentsin the region of the function block. Since relative to the functionblock moreover additional piping for connection of the respective filterelement can be omitted, in terms of thermal operating conditions, abalanced operating situation for the fluid system according to theinvention is achieved, to which the relatively thickly made wall partsof the function block can also contribute. Since, in addition, possiblediversion paths for the fluid are shortened, efficiency for the fluidsystem according to the invention is also improved in this respect.

In one especially preferred embodiment of the fluid system according tothe invention, the filter device is intended for the use of severalfilter elements through which flow can take place for filtration orbackflushing in both directions, some filter elements undertakingfiltration in one filtration position and at least one other filterelement can be backflushed for cleaning its active filter surface in abackflushing position. In this way automatic operation for the fluidsystem is possible, and, by way of automatic monitoring of fouling, abackflushing process can be carried out, using a pivoting device with amotor for which the respective filter elements can be pivoted insuccession into their filter position or backflushing position.

The fluid system according to the invention with its essentialcomponents, a function block with valve components and an insertedfilter device, has proven especially effective in use in so-called highpressure pump circuits, in which a high pressure pump is coupled to thefluid outlet of the fluid system, the fluid system then ensuring thatonly highly cleaned fluid is made available for further transport to thehigh pressure pump in order in this way to ensure a smooth pumpingprocess for the hydraulic circuit. It has been shown that otherwise evenextremely small dirt particles can be enough, particularly for speciallyconfigured high pressure pumps, to endanger their operation.

The fluid system according to the invention is detailed below using oneembodiment as shown in the drawings. The figures are schematic and notto scale.

FIG. 1 shows in the form of a hydraulic circuit diagram the use of thefluid system according to the invention for a so-called hydraulic highpressure pump circuit,

FIG. 2 shows in a perspective plan view the fluid system without thehigh pressure pump connected, and

FIG. 3 shows a longitudinal section through the fluid system as shown inFIG. 2.

FIG. 1 shows by way of example a fluid system for a pump circuit 10, inparticular in the form of a hydraulic high pressure pump circuit. Thispump circuit 10 has a function block which is designated as a whole as12 and which is symbolized in the hydraulic circuit diagram as shown inFIG. 1 with a dot-dash frame. The indicated function block 12 hasconnection sites in the form of one pump inlet 14 and one pump outlet16. The high pressure pump 18 which is connected to the connection sitesin this way is shown with its drive motor 20 and otherwise is made as anintake pump. Furthermore, the function block 12 has one fluid outlet 22to which there is connected a machine tool which requires a hydraulicmedium which is not detailed and which in turn is connected with itsfluid outlet to the fluid inlet 24 of the block 12. Furthermore there isa drain connection 26 which can lead, for example, to a chip conveyor ofthe indicated machine tool, which conveyor is not detailed. Thisapplication is only exemplary and instead of the machine tool there canbe some other hydraulic consumer, for example, in the form of ahydraulic transmission, a hydraulically triggerable hoist, hydraulicmotors of a fork lift and the like. Instead of the high pressure pump 18there can be a low pressure pump or the function block 12 can beconnected to the hydraulic circuit in another relation, for example, ina hydraulic heat exchanger circuit or hydraulic cooling circuit.

In this case, however, in the fluid-carrying path 28 to the machinetool, in addition to the high pressure switch 30, there are two highpressure 2/2-way valves 32, 34, on the input side of the directionalvalve 32 for safety reasons there being a pressure limitation valve 36whose output discharges into the backflushing line 38. On the outputside, the 2/2-way valve 32 is connected via an adjustable throttle valve40 likewise to the backflush line 38 so that largely unpressurizedcirculation via the throttle valve 40 for the fluid is possible. Anotherfluid-carrying path 42 is a corresponding fluid line which leads fromthe fluid inlet 24 of the machine tool to the pump inlet 14 of thefunction block 12. Adjacent to the fluid inlet 24 in turn a pressureswitch 44 is connected to the path 42, in this instance as a lowpressure switch, and downstream in the direction of the inlet 14 afilter device 46 follows, the degree of whose fouling can be detected byway of an electrical differential pressure switch 48 which sits in thebypass line of the path 42 to the filter device 46. If in one preferredembodiment the filter device 46 is designed as a backflushing filterdevice, as in this case, the backflushing line 38 is connected to thefilter device 46 and can be blocked by way of the backflushing valve 50.Furthermore, system values of the fluid circuit, such as, for example,the fluid pressure, can be retrieved by way of sensors, such as, forexample, a pressure gauge 52.

Supply of the machine tool with fluid can be set via the indicated2/2-way valves 32, 34 and, in the illustrated blocked state of thevalves 32, 34, the high pressure pump 18 by way of the throttle valve 40returns the quantity of fluid to the drain connection 26 of the functionblock 12. In this way the high pressure pump 18 can be made as aconstant pump with a permanent pump capacity and for the correspondingdemand for the machine tool, which is not detailed, the indicateddirectional valves 32, 34 are opened at discrete, definable timeintervals. In this way it is possible to constantly ensure filtrationoperation, in which fluid coming from the fluid inlet 24 is filtered bymeans of the filter device 46 and conveyed by way of the pump 18 isdischarged again into the hydraulic circuit 25 by way of the drainconnection 26 from the function block 12. If the filter device 46 ismade as a backflushing filter, the pertinent backflushing process can bemanually triggered; but preferably automatic backflushing operation isenvisaged, using a pivoting device for the individual filter elements,which device can be triggered by means of a motor 54; this will bedetailed below. The filter device 46 in the simplest case of dismountingcould, however, have only a single filter element which in the fouledstate could be replaced by a new filter element.

FIG. 2 shows the function block 12 in a perspective side view and asshown the components specified in FIG. 1 are reproduced in theirconfiguration in FIG. 2. As FIG. 2 shows, the entire function block 12with the integrated filter device 46 is structurally small in the formof a cuboid and all components of the pump circuit 10 as shown in FIG. 1can be analogously integrated in a space-saving manner into the functionblock 12.

Preferably, within the housing of the function block 12 thefluid-carrying paths, in particular the paths 28 and 42 with theirsecondary branch lines, are internally connected to one another suchthat a type of matrix structure of transverse and longitudinal rows offluid-carrying lines is formed, with place-holders integrated in thefunction block 12 for installation of the respective, already addressedvalve components. This place-holder solution, in addition to thematrix-like connecting structure by way of the respective connectinglines, makes it possible to manage a pronounced plurality of systemtasks in which depending on the desired function other valve componentscan also be set on the place-holders. A basic system once in use canalso be easily modified on site in the manner of a hydraulic module, inwhich other valve components replace the valve components usedpreviously. In particular, in this way, when large amounts of fluid andfluid pressures arise, the system can be adapted on site. Valvecomponents for the place-holders can be not only conventional pilot anddirectional valves, but also pressure limitation valves, nonreturnvalves and other triggerable pilot valves. The function block 12 builtin this way can also be integrated in this respect into other hydraulicfunction systems, for example, into the tank unit of a mobile hydraulicsystems which is not detailed.

The filter device 46 which is shown in FIG. 3 is designed as abackflushing filter device and has a cylindrical housing part 56 as thefilter housing. This filter housing part 56 viewed in the direction oflooking at FIG. 3 is seated on the top of the function block 12 andengages the corresponding housing part of the function block 12 by wayof a staggered projection 58. The housing part 56 widens to the outsideover the flange piece 60 which in this respect on its underside has areceiving channel for a ring seal which is not detailed and with whichthe interior of the housing part 56 can be sealed relative to theexterior. In this way the housing part 56 is detachably connected to thehousing of the function block 12 via the corresponding connecting screws62 (cf. FIG. 2). For fluid supply of the filter device 46 the housing ofthe function block 12 has one fluid channel 64 which leads to the fluidinput 24, and another fluid channel 66 which discharges into thebackflushing line 38 with a backflushing valve 50 which, made as ascrew-in cartridge as shown in FIG. 2, is inserted into the functionblock 12. Furthermore, the left half of the FIG. 3 shows the pump inlet14 of the function block 12 which discharges by way of the fluidconnection 68 into the interior of the function block 12 and into theinterior of the housing part 56 of the filter device 46.

Filter elements 70 which taper conically toward the top are insertedinto the filter device 46, for which instead of conical filter elements70 there can also be at least partially cylindrical filter elements (notshown). The indicated conical filter elements 70 which consistpreferably of so-called slotted hole screen filter elements are arrangedat distances from one another along a cylindrical are within the filterhousing part 56 and within the assignable housing part of the functionblock 12. For holding the individual filter elements 70 the functionblock 12 is provided with a cup-shaped recess 72 whose boundary wallends flush with-the inside wall of the housing part 56.

The arrangement as shown in FIG. 3 with the filter elements 70 is chosento be able to undertake backflushing; for function blocks of simplestructure, however, it is also possible to integrate only a singlefilter element in the function block 12 such that viewed in its axiallength it is more or less one half held in the function block 12, inparticular in the cup-like recess 72, and the other half projects fromthe underside into the interior of the housing part 56. In this way thefilter device 46 can be partially integrated in a very compact mannerwith its function elements in the function block 12 and otherwise thefilter elements 70 are also protected against mechanical damage by meansof the wall parts of the function block 12. Since the function block 12in the region of the receiver of the filter elements 70 is provided witha relatively great wall thickness, in this respect reliable chamberingof the active filter elements 70 is achieved in thermal terms; thisresults in a reduction in the loss of performance during filtration,especially if the medium to be filtered should be very different interms of the temperature of use.

In the selected arrangement as shown in FIG. 3, in addition to the twoillustrated filter elements 70, seen in the viewing direction and atradially equal distances to the indicated two filter elements 70, thereis another pair of filter elements 70 which on the one hand project outof the plane of the figure and on the other lie in the plane of thefigure which lies behind. Altogether therefore there are four filterelements 70 which are located diametrically to one another to thelongitudinal axis 74 of the filter device 46 and which are arranged inpairs opposite one another to the longitudinal axis 74. Otherconfigurations are conceivable here. Viewed in the direction of lookingat FIG. 3 the right-hand filter element 70 is located over the otherfluid channel 66 and is backflushed by means of the filtrate which isfound in the housing part 5. In doing so the filtrate from the outsideto the inside penetrates the filter element 70 which is to bebackflushed and dirt which has been removed by way of the backflushingquantity travels via the other fluid channel 66 and the backflushingvalve 50 which is then opened to the drain connection 26 of the functionblock 12, for example, in this way then the fouled backflush quantitycan be delivered to the chip conveyor of a machine tool which is notdetailed.

The other three filter elements 70 are connected annularly with theirrespective underside to the fluid channel 64 via which the unfilteredmaterial originating from the machine tool via the fluid input 24 issupplied to the filter device 46. Therefore filtration takes place viathe individual filter elements 70 from the inside to the outside and thefiltrate travels via the fluid connection 68 to the high pressure pump18 which is not detailed, as shown in FIG. 1. Since this high pressurepump 18 can implement very high intake capacities, according to theinvention care must be taken that the fluid connection 68 discharges inthe lower base region of the conical filter elements 70 so that it canoffer a corresponding resistance to a strong fluid flow. In the regionof the widened base support for the individual filter elements 70effective filtration takes place to an especially high degree; this inturn benefits the operation of the fluid system in terms of the overallenergy balance.

By means of a pivoting device 76 it is possible to move the individualfilter element 70 in succession from their filtration position into thebackflushing position and again into the filtration position, andperipheral motion for the individual filter elements 70 can take placeboth clockwise and also counterclockwise. The pivoting means 76 itselfhas a receiving part 78 for end-side accommodation of the individualfilter elements 70, the receiving part 78 by means of the motor 54 beingpivotable within the filter housing 56 around the pivoting axis 80. Thispivoting axis 80 is essentially congruent with the longitudinal axis 74of the filter device 46.

The receiving part 78 has two opposite end parts 82, 84, between whichthe individual filter elements 70 extend, the lower end part 84 havingpassages for fluid transport and the upper end part 82 being sealedfluid-tight to the exterior, that is, into the interior of the housingpart 56. If the housing part 56 is removed from the function block 12,via the upper end part 82 the filter elements 70 here can also be liftedout of the function block 12 for replacement by new elements.

The motor 54 of the filter device 46 can be an electric motor; butpreferably it is designed as a pneumatic motor. This pneumatic motor ischaracterized in that its cog-like driven part, depending on the pumpmotion of the piston parts of the pneumatic motor, executes alternatingback and forth motion, and this back and forth motion then can beconverted by means of a free-wheeling device 88 into a constant drivemotion in one drive direction for the pivoting axle 80 of the filterdevice 46. These free-wheeling devices for pneumatic motors areconventional so that they will no longer be detailed here. With theindicated drive concept it is, however, possible to convert thealternating back and forth motion of the pneumatic motor 54 as drivinginto pivoting motion by 90° at a time for the filter elements 70 bymeans of the pivoting device 76 in order in this way to always clean onefilter element 70 in the backflushing position in succession and tomaintain conventional filtration operation with the other three filterelements. The respective backflushing process for a filter element 70can therefore take place at more or less continuous time intervals; butit is also possible by way of difference pressure measurements, forexample, by means of an electrical differential pressure switch 48, todetermine on the respective filter elements 70 themselves when they areready to be backflushed.

As a result of the conical structure of the individual filter elements70, including the configuration of the cavity for the housing part 56,this arrangement has proven especially favorable in terms of energy infiltration operation, since the resistance offered in flow through thefilter elements 70 in conventional filtration operation, formed by theresistance of the parts of the housing 56, is distinctly reduced in thisway. Based on this configuration essentially laminar flow behavioroccurs; this helps reduce outflow resistance in conventional filtrationoperation and ensures that the filtered amount can be removed at thefluid connection 68 to the high pressure pump 18.

The already indicated slotted hole screen filter elements which arepreferably used, in the direction of the longitudinal axis 74 of thefilter device have tilted support rods around which a wire section iswound in individual turns, leaving gaps through which fluid can pass,there being a weld spot in the region of each contact point of the wiresection with the support rod. The gap size which is provided for freefluid passage, that is, the distance between two gaps, prevents passageof dirt if the particle size exceeds this gap width. Dirt which has,however, settled in the gaps can be reliably removed from the filterdevice by way of the described backflushing operation. The filterelement 70 which has been cleaned in this way then moves from thebackflushing position back into the filtration position and can bedirectly used there for further filtration operation.

For stable support of the filter elements 70, a configuration is alsoused in which the pivoting axle 80 on the end side is guided both in thefunction block 12 and also in the region of the upper wall parts of thefilter housing 56 of the filter device 46. The vibrations which occur atthe pneumatic motor 54 thus can be reliably diverted into the basestructure of the function block 12 both via the housing part 56 and alsovia the pivoting axle 80; this helps reduce the damaging portion of thevibration. The tightly packed coaxial arrangement of filter elements 70,relative to the pivoting axle 80, in this respect also ensures reliablyoperation in which the filter elements 70 as a whole are moved into theillustrated backflushing position.

1. A fluid system for a pump circuit (10), in particular a hydraulichigh pressure pump circuit, having a function block (12), in whosehousing fluid-carrying paths (28, 42) extend and to which valvecomponents (32, 34, 46) can be at least partially connected,characterized in that a filter device (46) with its filter housing (56)can be connected to the function block (12) such that at least onefilter element (70) is held in the installation space (72) of thefunction block.
 2. The fluid system according to claim 1, characterizedin that the filter device (46) is intended for the use of several filterelements (70) through which flow can take place for filtration orbackflushing in both directions, and that some filter elements (70)undertake filtration in one filtration position and at least one otherfilter element (70) can be backflushed for cleaning its active filtersurface in a backflushing position.
 3. The fluid system according toclaim 1, characterized in that the respective filter element (70) isheld more or less over half its axial installation length in theinstallation space (72) of the function block (12) and that thefluid-carrying paths (64, 68) which form the filter inlet and the filteroutlet are integrated in the function block (12).
 4. The fluid systemaccording to claim 1, characterized in that by means of a pivotingdevice (76) the respective filter element (70) can be moved from itsfiltration position into the backflushing position and back into thefiltration position, and that the pivoting device (76) has a receivingpart (78) for holding the filter elements (70), which part is pivotablewithin the filter housing (56) around the pivoting axle (80) by means ofa drive (54).
 5. The fluid system according to one of claim 1,characterized in that the filter housing (56) of the filter device (46)is seated on the function block (12) and holds more or less the top halfof the installation length of the respective filter element (70).
 6. Thefluid system according to claim 4, characterized in that the drive (54)acts by means of a free-wheeling device (88) on the pivoting axle (80)of the pivoting device (76) around which the individual filter elements(70) are coaxially located and which is guided to be rotatable on theend side in the filter housing (56) and in the function block (12). 7.The fluid system according to claim 6, characterized in that the drive(54) with its drive housing is seated on the housing of thefree-wheeling device (88) which is in turn seated on the filter housing(56).
 8. The fluid system according to claim 1, characterized in thatthe respective filter element (70) is made as a conical slotted holescreen filter element.
 9. The fluid system according to claim 1,characterized in that the function block (12) in addition to valvecomponents such as directional valves (32, 34) and pressure limitationvalves (36) has pressure switches (30, 44) and at least one pressuregauge (52).
 10. The fluid system according to claim 1, characterized inthat the hydraulic pump, in particular a high pressure pump (18), can beconnected from the exterior to the function block (12) to carry fluid.